Dunnage bags are very useful in protecting cargo during shipping. They are often used when shipping pallets of cargo by truck. The pallets are loaded into a trailer or cargo box, and the pallets are necessarily dimensioned so that they can be easily placed and removed. Thus, a certain amount of space remains between the pallets or between the pallets and the walls, such that the pallets can move around within the trailer or cargo box, and this in turn may cause damage to the goods or to the trailer or cargo box itself. Of course, this situation also pertains to other cargo, such as boxes, loose and free-standing cargo items, and to other cargo transportation, such as rail cars, containers and the like.
This situation is addressed by placing one or more inflatable dunnage bags between the pallets or other cargo, or between the pallets and the adjacent walls, and inflating the dunnage bags to fill the space and secure the palleted goods. Dunnage bags may also be used above the cargo to prevent cargo from bouncing, all with the purpose of having a securely packed and cushioned load.
Present dunnage bags are generally made of a multiple-ply lamination of heavy paper and a foil or plastic barrier. They generally have an inflation valve mounted in a wall of the dunnage bag, and the typical inflation valves are bulky and complex. For instance, one popular inflation valve has a lock-on fitting for receiving the mating fitting of an inflator hose, and a diffuser to prevent damage to the dunnage bag from high pressure inflation and from debris in the inflation air stream. These dunnage bags are sturdy and achieve acceptable cushioning. However, they tend to rub and chafe against the loads. This can impart a worn look to goods, as well as weaken the dunnage bag. Such dunnage bags are also expensive to make. They are bulky to ship to the point of use and bulky to store prior to use. The paper layers also tend to absorb moisture and odors. These dunnage bags also present a disposal problem because they are made of a combination of materials that cannot be recycled without separation, and are bulky waste items even after they are deflated.
The paper dunnage bags also present security issues, in that the dunnage bags are opaque and conceal whatever is behind them. When trucks and containers are opened at security checkpoints, inspectors should preferably be able to see the entire contents. If an inspector deems it necessary to deflate a dunnage bag in order to see the contents, provision must be made to replace or reinflate the dunnage bag at the checkpoint, or the contents will be unprotected.
In the course of developing the invention herein, it was recognized that an all thermoplastic dunnage bag would be compact for shipping to the point of use and for storage prior to use, would not absorb moisture and odors, and that an all thermoplastic dunnage bag would be easily recyclable after use. However, initial attempts to make an all plastic dunnage bag were not satisfactory, primarily because of difficulties in incorporating an inflation valve into the bag while maintaining the integrity of the bag.
Accordingly, it would be advantageous to have an improved dunnage bag that would overcome the disadvantages discussed above.